• Title/Summary/Keyword: amplitude of vibration

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A Study on Field Vibration for Fault Cause Analysis of Glass Insulator on High-speed Railway (고속철도 유리애자 파손원인을 위한 현장 진동 연구)

  • Kim, Young-Seok;Shong, Kil-Mok;Bang, Sun-Bae;Kim, Sun-Gu;Ryu, Young-Tae
    • Proceedings of the KIEE Conference
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    • 2008.05a
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    • pp.189-190
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    • 2008
  • This study was investigated a possibility of fault of glass insulator due to vibration on high-speed railway. The proper vibration of 1-glass insulator have many frequency band and high amplitude showed in high frequency than low frequency. The proper vibration of strut tube insulator was lowest 170Hz, highest 1.5kHz. The field signal amplitude of viaduct and open route were biggest moment pantograph of high-speed rail. The surface vibration(V3) amplitude of strut tube insulator was biggest. From the FFT analysis of viaduct and open route, the strut tube insulator effect by vertical vibration was big, the frequency was 82.5Hz and 105Hz, respectively. However, in comparison with the proper vibration of strut tube insulator, the resonance was not observed. Although the amplitude of insulator is high, the possibility of fault is low because the glass insulator deterioration by the accumulation of vibration do not happen.

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Experimental investigation of amplitude-dependent self-excited aerodynamic forces on a 5:1 rectangular cylinder

  • Wang, Qi;Wu, Bo;Liao, Hai-li;Mei, Hanyu
    • Wind and Structures
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    • v.34 no.1
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    • pp.73-80
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    • 2022
  • This paper presents a study on amplitude-dependent self-excited aerodynamic forces of a 5:1 rectangular cylinder through free vibration wind tunnel test. The sectional model was spring-supported in a single degree of freedom (SDOF) in torsion, and it is found that the amplitude of the free vibration cylinder model was not divergent in the post-flutter stage and was instead of various stable amplitudes varying with the wind speed. The amplitude-dependent aerodynamic damping is determined using Hilbert Transform of response time histories at different wind speeds in a smooth flow. An approach is proposed to extract aerodynamic derivatives as nonlinear functions of the amplitude of torsional motion at various reduced wind speeds. The results show that the magnitude of A2*, which is related to the negative aerodynamic damping, increases with increasing wind speed but decreases with vibration amplitude, and the magnitude of A3* also increases with increasing wind speed but keeps stable with the changing amplitude. The amplitude-dependent aerodynamic derivatives derived from the tests can also be used to estimate the post-flutter response of 5:1 rectangular cylinders with different dynamic parameters via traditional flutter analysis.

Study of the non-linearity of cable damper to enhance damping performance of stay cable (사장교 케이블의 감쇠성능 향상을 위한 댐퍼의 비선형성 연구)

  • Seo, Ju-Won;Koh, Hyun-Moo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.05a
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    • pp.147-156
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    • 2007
  • This study offers a design procedure of optimum cable damper for multi-mode vibration control with nonlinear damper and also investigate the relation between mode and amplitude dependency. The proposed multi-mode damping index, which is defined as a energy loss ratio of cable potential, is a main component of optimization problem of optimum nonlinear damper. In order to include the amplitude dependency of nonlinear damper, it is assumed to exist three kinds of multi-mode patterns such as ambient vibration, support excitation and rain-win induced vibration. The optimum damper exponent depends on amplitude patterns. In case of ambient vibration, optimum factor is less than 0.5. In case of support excitation or rain-wind induced vibration is between 0.5 and 1.0. In this study, the effects of cable sag and inclination angle are included in the asymptotic design equation of damped cable structures.

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Analyzing large-amplitude vibration of nonlocal beams made of different piezo-electric materials in thermal environment

  • Muhammad, Ahmed K.;Hamad, Luay Badr;Fenjan, Raad M.;Faleh, Nadhim M.
    • Advances in materials Research
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    • v.8 no.3
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    • pp.237-257
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    • 2019
  • The present article researches large-amplitude thermal free vibration characteristics of nonlocal two-phase piezo-magnetic nano-size beams having geometric imperfections by considering piezoelectric reinforcement scheme. The piezoelectric reinforcement can cause an enhanced vibration behavior of smart nanobeams under magnetic field. All previous studies on vibrations of piezoelectric-magnetic nano-size beams ignore the influences of geometric imperfections which are crucial since a nanobeam is not always ideal or perfect. Nonlinear governing equations of a smart nanobeam are derived based on classical beam theory and an analytical trend is provided to obtain nonlinear vibration frequency. This research shows that changing the volume fraction of piezoelectric phase in the material has a great influence on vibration behavior of smart nanobeam under electric and magnetic fields. Also, it can be seen that nonlinear vibration behaviors of smart nanobeam is dependent on the magnitude of exerted electric voltage, magnetic imperfection amplitude and substrate constants.

Vibration Analysis of an Amplitude Proportional Friction Damper System (변위비례식 마찰댐퍼 시스템의 진동해석)

  • 박동훈;최명진
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.5
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    • pp.171-179
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    • 2003
  • An Amplitude Proportional Friction Damper (APFD) is considered in order to improve the characteristics of Coulomb friction damper. The frictional force is proportional to the amplitude in APFD system and the system is non-linear as is Coulomb damper system. A free vibration analysis on the 1-DOF system has made to demonstrate the characteristics of the APFD system. The results show that APFD system has similar damping characteristics to the viscous damper. Also, the solution for the response of a base-excited system with APFD is developed through the application of a Fourier series to represent the frictional force of APFD. It is assumed that no stick-slips occur during any portion of the steady-state oscillation.

Development of Viscous Cabin Mount for Excavator (액체봉입형 Viscous 굴삭기 Cabin Mount 개발)

  • 김원영;전범석;박외경;강하근
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1997.10a
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    • pp.339-344
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    • 1997
  • Samsung Ltd. has developed a new-type cab mount for specific use on construct ion machinery subjected to strong vibration and multi-directional impact force. These all make it possible to achieve an excellent damping effect over a wide frequency range against large amplitude vibration as well as excellent insulation against small-amplitude vibration. This new mount make lower vibration and noise levels while increasing riding comfort at the same time. Characteristics of Cab mount were optimized through computer simulation, advanced bench testing, ODS testing, and a real equipment offroad testing.

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Vibration Analysis of Loudspeaker by Using Electronic Speckle Pattern Interferometry (전자 스페클 간섭계에 의한 스피커 진동 해석)

  • 김정규;노경완;강영준;김동우
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.11a
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    • pp.356-361
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    • 1996
  • Nowadays, Electronic Speckle Pattern Interferometry is a well established measuring technique with a wide range of industrial applications, particularly in the fields of deformation measurement and vibration analysis. Comparing with holographic inteferometry, it has some attractive features, which are rapid recording and reconstruction, satisfiable automation etc. Time-average ESPI was used to provide vibration mode shape of an object whose vibration amplitude is given as a fringe pattern. However, it is not possible to determine the direction of motions of a point on the object at any given time, because time-average method does not give any information about the phase of vibration. A better technique is stroboscopic method which can measure the amplitude and phase of vibrating surface. In this paper, loudspeakers were tested by these two methods and the mode shape and amplitude of vibration were visualized. As measured results, we can assume that these techniques will be applied directly in the loudspeaker industry.

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Correlation between Surface Roughness and Vibration in Slot Milling of AL7075-T6 (AL7075-T6의 슬롯가공 시 표면거칠기와 진동의 상관관계에 관한 연구)

  • Chun, Se-Ho
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.21 no.5
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    • pp.61-66
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    • 2022
  • This study investigated the characteristics and relationship between surface roughness and vibration according to the cutting conditions in the slot milling of AL7075-T6. The spindle speed, feed, and depth of cut were selected as independent variables and the amplitude of acceleration and surface roughness as dependent variables. Feed affected the surface roughness. As the spindle speed increased, the amplitude of vibration increased in the direction perpendicular to the feed direction. In addition, the amplitude of vibration and surface roughness showed a negative correlation. Under a given feed, the surface roughness improved as the vibration increased.

Serial pendulum DVA design using Genetic Algorithm (GA) by considering the pendulum nonlinearity

  • Lovely Son;Firman Erizal;Mulyadi Bur;Agus Sutanto
    • Structural Engineering and Mechanics
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    • v.89 no.6
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    • pp.549-556
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    • 2024
  • A serial pendulum dynamic vibration absorber (DVA) was designed to suppress the vibration of two degrees of freedom (Two-DOF) structure model. The optimal DVA parameters are selected using a genetic algorithm (GA) by minimizing the fitness function formulated from the system's frequency response function (FRF). Two fitness function criteria, using one and two target frequency ranges, were utilized to calculate the optimal DVA parameters. The optimized serial pendulum DVA parameters were used to reduce structural vibration under free and forced excitation conditions. The simulation study found that the serial pendulum DVA can effectively reduce the vibration response for a small excitation amplitude. However, the DVA performance decreases for a large excitation amplitude due to the nonlinearity of pendulum motion, and the percentage of vibration response attenuation is smaller than that obtained using a small excitation amplitude.

Analysis of derailment effect by vibration characteristics of rolling stock (철도차량의 진동특성에 의한 탈선영향 해석)

  • Lee K.S.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.355-360
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    • 2005
  • This paper describes how to measure the running safety using vibration accelerometers theoretically, and considers the effect of vibration parameters, such as amplitude and period, on the running safety by numerical analysis, which shows that the running safety are decreased as those parameters are increased.

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